Banana bunchy top virus (BBTV) is one of the most severe and widespread virus limiting production and distribution of planting material of banana (Musa spp.) crops in the world. In Democratic Republic of Congo (DRC), these crops play a major role in daily life of almost 70% of citizen. Many factors influence banana production negatively such as Banana bunchy top disease. Epidemiological survey was conducted in experimental stations and farmers’ fields for two consecutive seasons covering 72 sites in five provinces of south western of RDC. The objective of this study was to evaluate the presence and distribution of the Banana bunchy top virus in five provinces of South Western of DRC, with emphasis on the agro-ecological factors. A total of 174 Musa spp. leaves samples were collected and analyzed by PCR. The results revealed the presence of BBTV in all provinces investigated. The frequency of BBTV was 6.3% in Bandundu, 12.1% in Kasa?Oriental, 17.8% Bas Congo, 1.1% in Katanga and 7.5% Kinshasa Urban and Peri-urban. Results also revealed that BBTV occurred in experimental station and farmers’ fields, both having all cooking and dessert bananas. The high prevalence of BBTV seemed to be linked to multiple introductions of planting materials in the Bas Congo province during 1990 and 2002. However, the province of Katanga had not experienced the introduction of planting material. This factor would explain the lowest prevalence of Banana bunchy top virus in this province. The results indicated that there was a real need to facilitate access to genetically improved and healthy certified planting material in these provinces.
Banana and plantains (Musa sp.) are one of the most major crops in Democratic Republic of Congo. Plantain is considered as the second most important staple food after cassava (Manihot esculenta) [
Ten years ago, banana production and area planted have been reported to decline between 20% and 60% [
In most cases, the loss of 90% - 95% was observed in Cavendish variety [
Banana bunchy top disease (BBTD) caused by Banana bunchy top virus (BBTV), a virus of Nanoviridae family, genus: Babuvirus. Viral capsid has multi-component single-stranded DNA genomes encapsidated in small isometric particles (18 - 20 nm) [
In Democratic Republic of Congo, BBTD has been observed for the first time, around 1958, in the Kisangani region [
Five South Western province of the country, where prevailing different pedo-climatic conditions, were used for this study. The province of Katanga and Kasaï—Oriental; with a tropical climate type Aw6 according to Köppen climate classification—Were average daily temperature varies between 19˚C and 20˚C, the average annual rainfall is 1.226 mm. The floor of Katanga, in places, three different geological types. The soils of Kasaï Oriental province belong to the order of Kaolisols [
Epidemiological surveys were conducted in farmer’s fields over a 2 years period in Bas-Congo and Kinshasa urban and peri-urban areas, in Katanga, Kasaï—Oriental and Bandundu. A total of 72 sites were surveyed (
Using a questionnaire designed for this purpose, the producer responsible for the field was individually interviewed.
A result of the interviews with the producer, the banana leaf samples with typical symptoms and asymptomatic were collected. Banana leaf samples were stored in tubes as Bas samples, containing over anhydrous calcium chloride (Cacl2).
The total DNA was extracted from 100 mg of leaf samples by the method described by Dellaporta [
The frequency or incidence of Banana bunchy top virus in each province was calculated by establishing the ration between the total number of positive samples and the total number of samples tested, multiplied by 100.
For each field surveys, agro-ecological characteristics were taken into account. These include the production system in which the banana growing, genotype, cultivar type, source of planting material, monitoring the health status before planting, the type of fertilization, the number of fertilization banana during the complete cycle of the plant, the type of maintenance, treatment plant, intercropping system, altitude and crop age.
Observed parameters | South western Provinces surveyed | |||||
---|---|---|---|---|---|---|
(%) Bandundu | (%) Katanga | (%) Kassaï Oriental | (%) Kinshasa Urb & Peri Urbban | (%) Bas Congo | ||
1. Cropping System | ||||||
Planting around dwellings | 89.7 | 60.0 | 100 | 100 | 70.0 | |
Forest plantation | 5.2 | 0 | 0 | 0 | 15.0 | |
Experimental plantation | 5.2 | 40.0 | 0 | 0 | 15.0 | |
2. Genotype | ||||||
Plantain | 32.8 | 16.7 | 71.9 | 42.9 | 62.5 | |
Dessert banana | 67.2 | 83.3 | 28.1 | 57.1 | 37.5 | |
Banana beer | 0 | 0 | 0 | 0 | 0 | |
3. Type of variety (Planting material) | ||||||
Locale varieties | 72.4 | 76.7 | 87.5 | 100 | 100 | |
Improved varieties | 27.6 | 23.3 | 12.5 | 0 | 0 | |
4. Health status of planting material | ||||||
Known ( controlled and certified laboratoyr) | 0 | 0 | 0 | 0 | 0 | |
Unknown ( not certified, not checked) | 100 | 100 | 100 | 100 | 100 | |
5. Origin of planting material | ||||||
Research center | 5.2 | 0 | 0 | 0 | 15.0 | |
ONGDs or farmer’s association | 0 | 0 | 0 | 0 | 0 | |
Previous crop | 94.8 | 100 | 100 | 100 | 85.0 | |
6. Age of field | ||||||
1 to 6 months | 6.9 | 0 | 12.5 | 0 | 5.0 | |
7 to 12 months | 13.8 | 55.5 | 31.2 | 21.4 | 35.0 | |
More than 12 months | 79.3 | 44.4 | 56.2 | 46.7 | 60.0 | |
7. Type of fertization | ||||||
Organic | 86.2 | 56.7 | 100 | 78.6 | 77.5 | |
Mineral | 0 | 0 | 0 | 0 | 0 | |
Organic and Mineral | 1.7 | 33.3 | 0 | 0 | 7.5 | |
No fertization | 12.1 | 10.0 | 0 | 21.4 | 15.0 | |
8. Fertilizer application number | ||||||
Once at planting | 72.4 | 33.3 | 87.5 | 28.6 | 57.5 | |
Twice at planting and during the cultural cycle | 1.7 | 0 | 0 | 0 | 0 | |
Several times during the cycle | 12.1 | 50 | 12.5 | 57.1 | 27.5 | |
No fertilizer application | 13.8 | 16.7 | 0 | 14.3 | 15.0 | |
9. Traitement phytosanitairy | ||||||
No phytosanitary treatment | 100 | 96.6 | 100 | 100 | 100 | |
Phytosanitary treatment | 0 | 3.4 | 0 | 0 | 0 | |
10. Crops Association | ||||||
Yes | 67.2 | 30.0 | 59.4 | 64.3 | 80.0 | |
Not | 32.8 | 70.0 | 40.6 | 35.7 | 20.0 | |
11. Topography of the land | ||||||
Sloping | 15.5 | 0 | 0 | 7.1 | 5.0 | |
Flat land | 37.9 | 66.7 | 56.2 | 21.4 | 30.0 | |
Top of Hill | 22.4 | 10.0 | 0 | 21.4 | 32.5 | |
Valley | 24.1 | 23.3 | 43.8 | 50.0 | 32.5 | |
12. Other type of maintenance ( Weeding, hilling, desuckering, coppicing, staking) | ||||||
Yes | 25.9 | 0 | 0 | 21.4 | 12.5 | |
Not | 74.1 | 100 | 100 | 78.6 | 87.5 | |
13. Distribution of BBTV | ||||||
Prevalence of infecting plantation | 6.3 | 1.1 | 12.1 | 7.5 | 17.8 |
At the end of the investigations on the agro- ecological factors, the survey questionnaires were stripped and proportion of each parameter were calculated by comparing the number of observed parameter on the total number of fields investigated in the province. The logiciel R was used to analyze parameters, the standard deviation was calculated, the variance and the correlation between different parameters were established.
This analysis has allowed to evaluate each parameter and highlights the major constraints that effect banana cultivation in DRC.
A total of 174 symptomatic and asymptomatic samples, collected from five provinces of South Western democratic republic of Congo. The result revealed that 77 samples, or 44.8% of the plantations surveyed, analyzed were positive to Banana bunchy top virus (
The expected BBTV DNA fragment of 240bp was amplified from leaf tissue samples (Appendix
In the five provinces concerned by this study, Banana bunchy top virus was present in every type of cropping system (Figures 2 & 3). In farmer’s field, plantation, experimental station, both in forest and savannah area (
Results indicate that the level of prevalence of BBTV is variable in each province. Five provinces studied, the highest frequency of BBTV was observed in the Bas-Congo province (17.8%) (X2 = 69.27; ddl = 4; p = 0) and lowest frequency was observed in the Katanga province (1.1%). In between Kasai-oriental (12.1%) and Kinshasa urban and pre-urban (7.5%) and Bandundu has an infection rate of 6.3% recorded middle range prevalence (
To understand distribution of BBTV, agro-ecological characteristics of the sites surveyed were also studied; the results are shown in
· Planting material quality origin and varieties
Banana and plantain are vegetatively propagated plant. The crop thus requires the use of certified and healthy planting material. Results of this investigation indicate that planting materials used in both experimental station, and in farmer’s field are not always healthy and certified.
· Origin and varieties
Planting materials was of unknown healthy status in 100% of cases. The varieties used in research station and farmer’s field are local varieties, from previous culture and frequently of unknown origin (
· Cropping system, fertilization and use of fertilizers in banana cultivation
The survey of 72 sites in five provinces of the South Western of the country indicate that the banana and plantain are grown mostly in the cropping system of plantations around dwelling, where fertilization is mostly organic with a low frequency of fertilization. Most of the time, the supply of organic fertilizer is done before planting. This observation was performed in all types of cropping system.
In Katanga and Kinshasa urban and peri-urban, in respectively 50% and 57.1% of cases, the banana is fertilized at planting and during the cycle. The regular intake of leaves and waste are carried out (
The plant remains longer in the same place without renewed strain.
The age of the plantation is usually more than 12 months, and interviews are not made or if they are made they are limited to weeding-ridging (25.9% Bandundu, Kinshasa urban and peri-urban 21.4%, Bas Congo, 12.5%). The banana adapts in a moist environment at high humidity greater than 60%, with deep, loamy, well-drained pH between 4.0 and 8.0.
Nitrogen, phosphorus and potassium are major elements essential to the growth of the banana. The Ca and Mg are also needed to culture [
Productivity of the banana depends on natural conditions controlled or mastered by the best facilities, cultivation techniques, pesticides treatments etc. [
· Use of chemical treatment
Results of the investigations presented in
· Care cropping
Banana cultivation is carried out in bulk without additional crop tending. In the study area, Bandundu, Katanga, Kasaï Oriental, Kinshasa urban and peri-urban, bas Congo, bananas do not receive any cultural care, respectively in 74.1% of cases, 100%, 100%, 78.6% and 87.5%. In the remaining cases, in the province of Bandundu, Kinshasa urban and peri urban, bas Congo, the banana is just weeded, stumbled and staked to prevent the fall of the plant, related to the wind.
Banana bunchy top virus cause economically important disease. It is one of the major constraints for Musa germoplasm movement and vegetative propagation [
To control this disease requires that the current distribution, the agro-ecological characteristics where banana grown and agro-ecological factors promoting the distribution of the disease be determinate in order to develop strategies specific management BBTD.
The work reported here established the level of infection and distribution of Banana bunchy top disease in agro-ecological conditions of five provinces of Democratic Republic of Congo.
The results of this study reveal that Banana bunchy top disease is present in all provinces and is highly distributed.
In total, 44.8% of banana plantations in the South Western of the country are Banana bunchy top virus infected. This result joins the conclusions of investigations of other authors [
The province of Katanga has not experienced the introduction of improved planting material. This factor would explain the low incidence (1.1%) of Banana bunchy top virus.
Observation during our investigation confirmed that planting material use in all province of South Western of Democratic Republic of Congo are local varieties, uncertified healthy. The results join the conclusions of the work of other authors [
Surveys revealed that the uncontrolled exchange of non-certified and healthy planting materials, the use of local varieties of uncertain origin, contributes significantly to the spread of the disease. Observations made also by team Lava Kumar [
Examples of experimental fields in Katanga province, where samples are collected in experimental plantation of the faculty of Agronomy, where banana varieties harvested in different parts of the province have been field to explore their potential agronomic. Although the prevalence of BBTV is low in this province, it appears that in the experimental fields 2 samples in 10 are BBTV positives or (20%). Whether while in the province of bas Congo in research station an average two samples of 3 are positive BBTV.
Banana (Musa spp.) is a culture of high agricultural potential in DRC [
Results obtained in this study suggest that, the banana yield decline in south western of DRC is partly be caused by Banana bunchy top virus. It is probably only one of number of factors that are responsible for the decline. Banana is cultivated several year-round in some place. This practice contributes not only to a decrease in land fertility, but to the accumulation of other diseases like BBTV [
Banana bunchy top virus is established and is spreading across agro-ecological conditions where banana is cultivated, particularly in South Western democratic republic of Congo. BBTV is also presented in experimentation station. In view of the major role to be played by the research institution, the frequency of BBTV observed is very high and worrying.
There is a real need for establishing control strategies at different levels: among farmers and state level:
· Levels of farmers: the learning to recognize the BBTD symptoms, the destruction of infected plants and the use of healthy planting material certified.
· Level of state: control strategies including the creation of buffer zones quarantine, the development of biological control methods against the vector (Pentalonia nigronervosa Coquerel), the development of varieties resistant, sensitive, effective and appropriate to the context of Congolese agriculture, support institutions dedicated to the control of planting material. The implementation of the strategies will support the control of Banana bunchy top virus.
We thank the Direction of Statistics of the National Institute of Agronomic Research of INERA/ DRC, the Belgian development agency which funded this study, the technical staff and all the technicians of the International Plant Clinic and any person who, in one way or another to contribute to this study.